Robotic apparatus and method for mounting a valve stem on a wheel rim

ABSTRACT

An apparatus and method for mounting a valve stem to the rim of an vehicle wheel includes engaging a valve stem with a robotic manipulator, moving the valve stem relative to the rim along a programmable path of travel, coaxially aligning the valve stem with the aperture in the rim, and inserting the valve stem through the aperture in the rim. Preferably, the aperture location in the rim is determined at a gauging station by a machine vision system. If necessary, a power-actuated nut runner is used to tighten a nut over the valve stem. Alternately, the gauging station can use a table which rotates the wheel about a central axis, and an optical sensor detects the location of the aperture. Optionally, a probe mounted on the gauging station can be extended into the aperture to confirm the aperture position and to reposition the rim slightly if required.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of Ser. No. 10/264,746, filedon Oct. 4, 2002, now U.S. Pat. No. 6,886,231 issued May 3, 2005 andwhich is a continuation-in-part of Ser. No. 09/344,042 filed on Jun. 25,1999, now U.S. Pat. No. 6,481,083, issued Nov. 19, 2002.

FIELD OF THE INVENTION

The present invention relates to the assembly of wheels for automotivevehicles, and more specifically to a new apparatus and method formounting a valve stem on a wheel rim.

BACKGROUND OF THE INVENTION

The great majority of wheels produced for automotive vehicles include ametal rim, a tubeless tire mounted on the rim, and a valve stemprojecting through an aperture in the rim to communicate with theinterior of the tire and permit inflation.

In the past, automobile wheels have been assembled using primarilymanual labor. In particular, the mounting of the valve stem to the rimhas been accomplished by a hand-held stem inserter tool such as thatdisclosed in U.S. Pat. Nos. 3,852,839 and 4,807,343. Similarly, themounting of the tire on the rim has involved a worker placing the rim ina fixture, positioning the tire partially over the rim, and actuating amachine for pressing the tire downwardly into position around the rim.Manual processes are expensive due to the high cost of manual labor andamount of cycle time involved in completing the assembly of one tire ona rim, and are subject to human error potentially producing defectivewheels.

It is desirable to adapt modern robotic and machine vision systems toautomate the manufacture of mounted tires.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for the highvolume, low cost assembly of valve stems to wheel rims. The presentinvention provides a completely automated method and apparatus using arobotic manipulator to handle the valve stem or rim during assembly. Thepresent invention provides an automated assembly apparatus and methodadapted to assemble different types and sizes of rims having valve stemmounting apertures at different locations and aligned at differentangles. The present invention is intended for use with both normal sizedand miniature rims (such as those used for compact spares on somevehicles) having an aperture passing therethrough for receiving atubular valve stem. According to the invention, the rim is positioned ina gauging station where the location and alignment of the aperture isdetermined.

In one embodiment, a robotic manipulator grasps the wheel located at thegauging station and, under the direction of an electronic controlsystem, moves the rim to a mounting station where a valve stem isretained. The manipulator positions the rim such that the aperture is inalignment with the longitudinal axis of the valve stem, and the wheelrim is then moved relative to the valve stem to insert the valve stemthrough the aperture in the rim.

In another embodiment, a robotic manipulator grasps the stem located atthe valve stem delivery station and, under the direction of anelectronic control system, moves the valve stem to the mounting stationwhere the valve stem is to be assembled to the rim. The manipulatorpositions the valve stem such that the aperture in the rim is inalignment with the longitudinal axis of the valve stem, and the valvestem is then moved relative to the rim to insert the valve stem throughthe aperture in the rim.

According to the present invention, the gauging station can use amachine vision system to determine the radial and circumferentiallocation of the aperture on the rim and the angle which the central axisof the aperture makes with the central axis of the rim. These factorscan be determined, at least in part, by programming the machine visionsystem to recognize certain features of the rim which identify the rimas being an example of one of a plurality of pre-programmed types andsizes of rims. The aperture location and/or alignment information foreach type and size of rim is stored for retrieval based on input fromthe machine vision system.

The data describing the location and alignment of the aperture isrelayed to the control system so that the control system can direct therobotic manipulator to properly position the rim or valve stem inrelation to the other at the mounting station.

According to the present invention, the automated assembly apparatus caninclude a plurality of valve stem delivery stations, each containing adifferent type and/or size of valve stem. The machine vision systemidentifies a rim as being an example of one of the plurality ofpre-programmed types and directs the robotic manipulator to pick up thevalve stem from the appropriate valve stem delivery station, move thevalve stem to the mounting station, and insert the valve stem into theaperture identified in the stationary wheel rim by the machine visionsystem. This allows the assembly apparatus to simultaneously handledifferent types and/or sizes of rims and mount the appropriate typeand/or size of valve stem to each rim.

In an alternative embodiment of the invention, the gauging station caninclude a rotating table for receiving the wheel rim and rotating wheelrim about a central axis, and an “electric eye” optical sensor fordirecting a beam of infrared light onto the rim. As the rim rotatesthrough the beam, the presence or lack of a reflection of the light beamis used to detect the location of the aperture, and rotation of thetable is stopped when the aperture is in alignment with the beam. Ifdesired, a probe mounted on the gauging station can be extended toproject into the aperture to confirm the aperture is in the desiredposition and, if necessary, reposition the rim slightly to provide aprecise positioning of the aperture. In this embodiment of the gaugingstation, the aperture is always in the same position relative to thegauging station, and the robotic manipulator can either grasp the rimprior to moving the rim to the mounting station, or the roboticmanipulator can grasp the appropriate valve stem prior to inserting thevalve stem through the located aperture in the wheel rim, or the wheelrim can be moved along the conveyor in a known orientation to a mountingstation separate from the gauging station for insertion of theappropriate valve stem.

According to the present invention, a power-actuated nut runner can beused to tighten a nut over a threaded portion of the valve stem tosecure the valve stem in connection with the rim. The nut runner caneither be mounted on the robotic manipulator, or can be mounted on oradjacent to the mounting station.

According to the present invention, a valve stem delivery apparatus canbe disposed on or adjacent the mounting station and can supply acontinuous stream of valve stems for mounting to rims by the roboticmanipulator at the mounting station.

In the present invention, the valve stem can either be heldsubstantially stationary relative to the mounting station with therobotic manipulator urging the wheel rim onto the valve stem, or thewheel rim can be held substantially stationary relative to the mountingstation with the robotic manipulator urging the valve stem through theaperture in the wheel rim. In either case, it has been found that thepresent invention of inserting the valve stem through the apertureprovides for an accurate, positive, and repeatable insertion of thevalve stem into the aperture.

In the present invention, the robotic manipulator can transfer theassembled rim and valve stem from the mounting station to a subsequentwork station and release the rim with the valve stem in a consistent,desired reference position relative to the work station. This allowssubsequent assembly steps to be performed on the rim, such as mountingof a tire, to be accomplished with reference to the position of thevalve stem on the rim.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like reference numerals refer to like parts throughout theseveral views, and wherein:

FIG. 1 is a perspective view of an apparatus according to the presentinvention including a machine vision system associated with a gaugingstation;

FIG. 2 is a partial side view of the mounting station with a rimpositioned in preparation for being urged downwardly over a valve stemby a robotic manipulator according to one embodiment of the presentinvention;

FIG. 3A is a partial side view of the mounting station with a miniaturerim prior to assembly with the valve stem;

FIG. 3B is a partial side view of the miniature rim of FIG. 3A afterassembly with the valve stem;

FIG. 4 is a perspective view of a gauging station according to thepresent invention including an electric eye;

FIG. 5 is a perspective view of a mounting station according to oneembodiment of the present invention having a nut runner;

FIG. 6 is a plan view of an assembly line according to one embodiment ofthe present invention having multiple mounting stations;

FIG. 7 is a perspective view of an alternative embodiment of the presentinvention illustrating a wheel rim conveyor having an aperture locatingand/or wheel rim type and/or size gauging station using either a machinevision system or optical sensor, and a robotic manipulator for graspingan appropriate valve stem from a valve stem delivery station forinsertion of the valve stem through the aperture in a stationary wheelrim; and

FIG. 8 is a plan view of the robotic manipulator, wheel rim conveyorincluding a gauging station and a mounting station, and a valve stemdelivery station of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED AND ALTERNATIVE EMBODIMENTS

As seen in FIG. 1, an automated assembly line 8 for mounting valve stemsto wheel rims includes an input conveyor 10 for conveying rims 12 in asingle-file fashion, a gauging station 14 adjacent the end of the inputconveyor, a valve stem mounting station 16 located adjacent the gaugingstation, an output conveyor 18 for carrying the assembled wheel/stemunits away, and a robotic manipulator 20 for transferring the rims fromthe gauging station to the mounting station and then to the outputconveyor.

Operation of the automated assembly line 8 is monitored and directed byan electronic control system, indicated schematically at 22. The controlsystem 22 includes input/output means such as a display screen 22 a anda keypad 22 b for allowing a human operator (not shown) to receiveinformation regarding the status of the line and program desired modesof operation. The control system unit 22 can be connected to and/orintegrated with other information processing systems so that theassembly line 8 can be monitored and controlled from one or morelocations remote from the line itself. For example, the control system22 can be connected with a plant-wide network to allow the operation tobe controlled and monitored from a computer station 23 located at someremote location.

The input conveyor 10 is shown to be of the type including a series ofparallel rollers, however it can alternatively be any of the varioustypes of conveyors known in the material handling art. The rims 12 areof the type used for automotive vehicle wheels for receiving tubelesstires (not shown), and have opposite first and second flanges 12 a, 12b. The first flange 12 a has an aperture 26 formed therethrough forreceiving a valve stem 28.

The gauging station 14 is located at the end of the input conveyor 10and includes a closed circuit video camera 30 mounted above the conveyorline on a support frame 32. The video camera 30 is of the type used inmachine vision systems and is directed downwardly so that the cameraimages the upper flange 12 a of a rim located in the gauging station.The output of the video camera 30 is communicated to the control system22 by a cable 34.

The robotic manipulator 20 is of the type commonly used in modernmanufacturing operations and includes an arm 36 capable of compound,multi-axial movement. A gripper 38 at the end of the arm 36 has fingers40 actuable to alternatively grasp and release the wheel rim 12. A nutrunner 42 is mounted on the robotic manipulator 20 adjacent the gripper38. The nut runner 42 is a pneumatically or electrically powered devicefor rotating a threaded nut over a matingly threaded male component. Amagazine 44 for holding a large number of nuts and feeding the nuts tothe nut runner 42 is also mounted on the arm 36. The robotic manipulator20 is electrically connected with the control system 22 by a cable 46.

The valve stem mounting station 16 includes a base 48 and a shaft 50extending generally horizontally therefrom. The shaft 50 is rotatablewith respect to the base 48 and is powered by, for example, a electricservomotor (not shown). A stem holding finger 52 projects from the shaft50 for rotation therewith, and is small enough to fit within the hollowinterior of a valve stem 28. A vibratory sorting and conveying mechanism54 of the type known in the art of automated assembly is mounted on ornear the base 48 and supplies a stream of valve stems 28 to an outputposition 55 adjacent to the finger 52.

Rotation of the shaft 50 moves the finger 52 between a first positionwhere the shaft points toward the output position 55 of the stemconveying mechanism 54 so that a stem 28 can slide over the finger, anda second position where the finger 52 and valve stem 28 carried thereonpoint generally upward.

During operation of the automated stem mounting apparatus, rims 12 areplaced on the input conveyor 10 at an upstream location such that theflange 12 a having the valve stem aperture 26 formed therethrough isoriented upwardly. As a rim 12 reaches the end of the input conveyor 10,the rim comes into contact with one or more blocks 56 to stop the rimdirectly below the video camera 30 in the gauging station 14. When therim 12 is stationary in the gauging station 14, the control system 22activates the video camera 30 to image the rim. If ambient lighting inthe vicinity of the conveyor is not sufficient to allow the video camera30 to acquire a high resolution image, additional light fixtures 58 canbe provided.

The image produced by the video camera 30 is relayed to the controlsystem 22 where a digital pattern recognition program of the type knownin the machine vision art is used to determine the location of the valvestem aperture 26 relative to the gauging station 14 and/or the type ofwheel rim and/or size of wheel rim located at the gauging station. Theimage produced by the camera can provide sufficient information for alookup function to be processed with respect to a stored data base forthe angle α (see FIG. 2) between the central axis 60 of the aperture 26with respect to the central axis 62 of the particular rim 12 currentlybeing imaged at the gauging station.

It is possible for the pattern recognition software to be configured todetermine the location and/or alignment of the aperture 26, at least inpart, by identifying physical features of the rim 12 other than theaperture itself. For example, features such as the spoke pattern and/orthe diameter of the rim 12 can be used to identify the rim as being anexample of one of several types and/or sizes of rims recognized by thesoftware. The aperture location and/or alignment information for theserim types and/or sizes is stored as part of the pattern recognitionsoftware. The aperture alignment angle α can be particularly difficultto determine through direct measurement by the machine vision system,and so it can be advantageous to have this parameter stored andretrieved once the type and/or size of rim is identified.

Identification of the type and/or size of each rim processed by theassembly line 8 can also be used in other phases of the tire assemblyprocess. This knowledge can be used, for example, to ensure that thecorrect tire for each rim is supplied to an automated tire mountingassembly line following the stem mounting line in a plant.

Next, the control system 22 actuates the robotic manipulator 20 to graspthe rim 12, lift the rim from the gauging station 14, and move the rimto the mounting station 16. The location and alignment of the aperture26, as determined by the machine vision system, is used by the controlsystem 22 to direct the robotic manipulator 20 to rotate the rim 12 asnecessary to position the aperture 26 in alignment with the valve stem28 on by the stem holding finger 52 and with the nut runner 42 (see FIG.2).

When the aperture 26 is aligned with the valve stem 28, the roboticmanipulator 20 urges the rim 12 toward the valve stem 28 so that thevalve stem is inserted through the aperture 26. It is also possible forthe mounting station 16 to include means for moving the valve stem 28toward the rim 12 and into the aperture 26, rather than holding the stemstationary as the rim is urged downwardly.

As seen in FIG. 2, insertion of the valve stem 28 through the aperture26 also results in the stem sliding into the end of the nut runner 42.The nut runner 42 is then activated to place a nut over the end of thevalve stem 28 and rotate and tighten the nut, thereby securing the valvestem in connection with the rim 12.

Generally speaking, only certain specialty valve stems (for example,those having an integral pressure transducers for on-vehicle monitoringof the tire pressure) must be secured to the rim 12 with a nut. The morecommonly used types of valve stems are secured to the rim 12 merely byurging the valve stems through the aperture 26. Accordingly, the nutrunner 42 can be dispensed with on a valve mounting apparatus used withvalve stems not requiring a nut. Alternatively, the nut runner can beretained and the control system programmed to perform or omit the nuttightening step depending on the type of valve stem and rim beingassembled at any particular time.

After the valve stem 28 is secured to the rim 12, the roboticmanipulator 20 is actuated by the control system 22 to lift the rim 12away from the mounting station 16, move the rim to a station forsubsequent processing, and place the rim thereon. In the embodiment ofthe invention shown in FIG. 1, the subsequent processing station is anoutput conveyor 18 including a series of platforms 64 where eachplatform is adapted to receive a rim 12.

FIG. 6 shows an assembly line 200 having three separate stem mountingstations 116, 216, 316 each loaded with a different type of valve stem,128, 228, 328 respectively. The different valve stems can be intendedfor use with different types and/or sizes of rims to be handled by theassembly line 200, and/or the stems can be different types and/or sizesto be alternatively mounted to a single type and/or size of rim. Forexample, the assembly line 200 is shown configured to process twodifferent types and/or sizes of rims: a first type of rim 112 forpassenger cars and a second type of rim 212 for light trucks. In thisexample, the passenger car rims 112 can be fitted with either a standardvalve stem 128 or a special valve stem 228 having an integral pressuretransducer, while all light truck rims 212 are to be fitted with a heavyduty valve stem 328.

As each rim reaches the gauging station 14, the video camera 30 imagesthe rim and the control system 22 identifies the rim as either a car rim112 or a truck rim 212, based on programmed physical features asdescribed above. The control system 22 then directs the roboticmanipulator 20 to move the rim to whichever of the mounting stations116, 216, 316 is loaded with the correct stem for that rim. The nutrunner 42 mounted to the robotic manipulator 20 is activated to thread anut over the end of the valve stem only when a stem requiring suchaction, such as pressure transducer stem 228, has been mounted to therim.

For the passenger car rims 112, the selection between the standard stem128 and the pressure transducer stem 228 depends on planned productionschedule information previously programmed into the control system 22 bya human operator using the key pad 22 b or remote computer 23. Theoperator can select, monitor, and change all phases of operation of theassembly line using the display screen 22 a and key pad 22 b or theremote computer 23. Cumulative production data is stored by the controlsystem 22 and can be reviewed by the operator at any time.

The assembly line 200 of FIG. 6 also differs from that of FIG. 1 in thatthe gauging station 14 is not located at the end of the input conveyor10, but rather at a midpoint of the conveyor. Any rim that does not meetcertain production or quality control criteria programmed into thecontrol system 22 is placed back on the input conveyor 10, which carriesthe “reject” rim away. For example, in FIG. 6 a car rim 112′ has beenreplaced on conveyor 10 after imaging because the car rim arrived at thegauging station 14 out of sequence. By way of example and notlimitation, the control system 22 can be programmed to process rims onlyin groups of four identical rims advancing in series down the assemblyline, and since the car rim 112′ followed two light truck rims 212, thecar rim was removed from the production sequence for failing to meet thepreprogrammed criteria. Other reasons for taking a rim out of theproduction sequence can include the rim being positioned on the inputconveyor with the aperture 26 oriented downwardly, or some incorrect rimgeometry making the rim unrecognizable to the control system. Productionirregularities such as these can generate a message for display on thevideo screen 22 a and/or the remote computer 23 to alert the operator toa problem requiring immediate attention.

FIG. 6 also depicts a mode of operation where the robotic manipulator 20deposits each rim 112, 212 onto a conveyor platform 64 with the mountedvalve stem at a consistent and known reference angular position relativeto the platform, in this case at twelve o'clock with respect to thedirection of movement of conveyor 18. Having the mounted valve stem in areference position can be desirable for accomplishing subsequentassembly steps. For example, when mounting a tire (not shown) to a rimit is generally preferable to align the heaviest point on thecircumference of the rim with the lightest point on the circumference ofthe tire in order to achieve as close to a perfectly balanced wheel/tirecombination as possible. If it is known that the valve stem is theheaviest point on the rim, placement of the rim on the output conveyorwith the stem at a reference position will eliminate the necessity oflocating the valve stem again prior to mounting a tire to the rim.

One advantage of the apparatus and method according to the presentinvention is that the robotic manipulator 20 is able to execute acomplex, non-linear motion to insert the valve stem through the rim ifthis is necessary due to the geometry of the rim or some otherconsideration. Some rims, such as those used as compact spares to savespace and weight in passenger vehicles, have flanges that are too closetogether to allow the axes of the valve stem and of the aperture to bealigned with one another and the stem inserted into the aperture bymoving the rim and the stem in a straight line relative to one another.

A possible mode of operation is depicted in FIGS. 3A and 3B, which showa valve stem 28 being mounted to an undersized rim 66. The controlsystem 22 is programmed to recognize an undersized rim 66 and direct therobotic manipulator 20 to position the rim 66 such that the tip of thevalve stem 28 is adjacent aperture 26, but with the central axis of theaperture at an angle to the longitudinal axis of the stem (see FIG. 3A).The robotic manipulator 20 then rotates the rim 66 clockwise about anaxis extending out of the plane of FIG. 3, while simultaneously movingthe rim vertically downward to slide the valve stem 28 into the aperture26 (see FIG. 3B).

FIG. 4 depicts an alternative embodiment of a gauging station 114 foruse in conjunction with the present invention. The gauging station 114includes a motor-driven rotating table 68 located at the end of theinput conveyor 10 and an “electric eye” optical sensor 70 disposed abovethe table 68. The optical sensor 70 uses a beam of infrared light, as isknown in the art.

The sensor 70 includes a transmitter 70 a mounted above the rotatingtable 68 and aimed to direct a beam onto a rim 12 located on the table,the beam striking the flange 12 a at a point located at the same radialdistance from the central axis of the rim as the aperture 26. A receiver70 b is located adjacent the transmitter 70 a so that the beam willstrike the receiver 70 b when the beam reflects off of the flange.Alternatively, the receiver 70 b can be mounted below the upper flange12 a of the rim and aligned with the transmitter 70 a to receive thebeam when the beam passes through the aperture 26.

As a rim 12 reaches the end of the input conveyor 10, the rim slidesonto the rotating table 68 and is stopped at that point by one or morestop blocks 69 to precisely position the rim 12 so that a central axisis in coaxial alignment with the axis of rotation of the rotating table68. The optical sensor 70 is activated, and the rotating table 68 beginsto turn so that the beam sweeps around the circumference of the flange12 a at the proper radial distance from the center of the rim to passthrough the aperture 26 when the aperture 26 comes into alignment withthe beam.

As long as the beam strikes the flange 12 a, the beam is reflected backto the receiver 70 b. When the aperture 26 comes into alignment with thebeam, the beam is no longer reflected back to the receiver 70 b and thischange in the condition of the optical sensor 70 causes the rotatingtable 68 to stop so that the aperture 26 remains in alignment with thebeam. The robotic manipulator 20 then grasps the rim 12 and moves therim from the gauging station 114 to the mounting station 16. Theaperture 26 is always in the same location relative to the gaugingstation 114 and the robotic manipulator 20, so the control system 22directs the manipulator to execute the same motion each time themanipulator moves a rim 12 to the mounting station 16 and positions therim for insertion of the valve stem 28.

It can be desirable to provide a mechanical means for preciselypositioning the rim 12 relative to the gauging station 114 before therim is grasped by the robotic manipulator 20. This can be achieved by aprobe 72 mounted adjacent a rotating table 68 and capable of beingextended upwardly to enter the aperture 26 after the rotating table 68has stopped turning. The probe 72 has a tapered tip so that the tip willenter the aperture 26 even if the aperture 26 is slightly misalignedwith the probe 72, and as the probe 72 extends fully into the aperture26 the probe will reposition the rim 12 somewhat to correct anymisalignment.

FIG. 5 depicts an alternative embodiment of a mounting station 116 foruse with the present invention where a nut runner 142 is mounted on oradjacent the mounting station 116 rather than being disposed on therobotic manipulator. FIG. 5 shows the nut runner 142 in a raisedposition where there is sufficient clearance between the valve stemholding finger 52 and the lower end of the nut runner 142 for the rim 12to be placed over a valve stem 28 positioned on the finger. After therim 12 has been placed over the valve stem 28, the nut runner 142 movesor telescopes downwardly (not shown) over the valve stem to place a nutover the stem and tighten the nut. A vibratory sorting and conveyingapparatus 74 of the type known in the art feeds nuts to the nut runner142.

Referring now to FIGS. 7 and 8, an automated assembly 408 for mountingvalve stems to wheel rims includes an input portion 410 of a conveyorfor conveying rims 412 in a single-file fashion, a gauging station 414adjacent the end of the input portion 410 of the conveyor, a valve stemmounting station 416 located adjacent to the gauging station 414, anoutput portion 418 of the conveyor for carrying the assembled wheel/stemunits away, and a robotic manipulator 420 for transferring the valvestems from the valve stem delivery station to the mounting station andfor inserting the valve stem through an aperture formed in each rim 412prior to being discharged along the output portion 418 of the conveyor.

Operation of the automated assembly line 408 is monitored and directedby an electronic control system indicated schematically at 422. Thecontrol system 422 includes input/output means, such as a display screen422 a and a keyboard 422 b for allowing a human operator to receiveinformation regarding the status of the line and to program desiredmodes of operation. The control system 422 can be connected/integratedwith other information processing systems so that the assembly line 408can be monitored and controlled from one or more locations remote fromthe line itself. For example, the control system 422 can be connectedwith a plant-wide network to allow the operation to be controlled andmonitored from a computer station 423 located at some remote location.

The input portion 410 of the conveyor is shown to be of the typeincluding a series of parallel rollers, however it can alternatively beany of the various types of conveyors known to the material handlingart. The rims 412 are of the type used for automotive vehicle wheels forreceiving tubeless tires, and have opposite first and second flanges 422a, 422 b. The first flange 412 a has an aperture 426 formed therethroughfor receiving a valve stem 428.

The gauging station 414 is located at the end of the input portion 410of the conveyor and includes a closed circuit video camera 430 mountedabove the conveyor line on a support frame 432. The video camera 430 isof the type used in machine vision systems and is directed downwardly sothat the camera images the upper flange 412 a of a rim located in thegauging station. The output of this video camera 430 is communicated tothe control system 422 by a cable 434.

The robotic manipulator 420 is of the type commonly used in modemmanufacturing operations and includes an arm 436 capable of compound,multi-axial movement. A gripper 438 at the end of the arm 436 hasfingers 444 actuable to alternatively grip and release the valve stem428. A nut runner can be mounted on the robotic manipulator 420 adjacentthe gripper 438. The nut runner can be a pneumatic or electricallypowered device for rotating a threaded nut over a matingly threaded malecomponent. A magazine can be provided for holding a large number of nutsand feeding the nuts to the nut runner. The magazine for holding thenuts can also be mounted on the arm 436. The robotic manipulator 420 iselectrically connected with the control system 422 by a cable 446.

The valve stem delivery station 417 includes a base 448 and a shaft 450extending generally horizontally therefrom. The shaft 450 is rotatablewith respect to the base 448 and is powered by, for example, an electricservo motor. A stem holding finger 452 projects from the shaft 450 forrotation therewith and is small enough to fit within the hollow interiorof a valve stem 428. A vibratory sorting and conveying mechanism 454 ofthe type know in the art of automated assembly is mounted on or near thebase 448 and supplies a stream of valve stems 428 to an output portion455 adjacent to the finger 452.

Rotation of the shaft 450 moves the finger 452 between a first positionwhere the shaft points toward the output position 455 of the stemconveying mechanism 454 so that the stem 428 can slide over the finger,and a second position where the finger 452 and valve stem 428 carrythereon point generally upward.

During operation of the automated stem delivery apparatus, rims 412 areplaced on the input portion of the conveyor 410 at an upstream locationsuch that the flange 412 a having the valve stem aperture 426 formtherethrough is oriented upwardly. As a rim 412 reaches the end of theinput portion 410 of the conveyor, the rim comes in contact with one ormore blocks to stop the rim directly below the video camera 430 in thegauging station 414. When the rim 412 is stationary in the gaugingstation 414, the control system 422 activates the camera 430 to imagethe rim. If ambient lighting in the vicinity of the conveyor is notsufficient to allow the video camera 430 to acquire a high resolutionimage, additional lighting fixture 458 can be provided.

The image produced by the video camera 430 is relayed to the controlsystem 422 where a digital pattern recognition program of the type knowin the machine vision art is used to determine the location of the valvestem aperture 426 relative to the gauging station 414 and/or the type ofwheel rim and/or size of wheel rim located at the gauging station. Theimage produced by the camera can provide sufficient information for alookup function to be processed with respect to a stored data base forthe angle α between the central axis of the aperture 426 with respect tothe central axis of the particular rim 412 currently being imaged at thegauging station, as previously described with respect to FIG. 2.

It is possible for the pattern recognition software to be configured todetermine the location and/or alignment of the aperture 426, at least inpart, by identifying physical features of the rim 412 other than theaperture itself. For example, features such as the spoke pattern and/orthe diameter of the rim can be used to identify the rim as being anexample of one several types and/or sizes of rims recognized by thesoftware. The aperture location and/or alignment information for theserim types and/or sizes is stored as part of the pattern recognitionsoftware. The aperture alignment angle α can be particularly difficultto determine through direct measurement by the machine vision system,and so it can be advantageous to have this parameter stored andretrieved once the type and/or size of rim is identified.

Identification of the type and/or size of each rim processed by theassembly line 408 can also be used in other phases of the tire assemblyprocess. This knowledge can be used, for example, to insure that thecorrect tire for each rim is supplied to an automated tire mountingassembly line following the stem mounting line in a plant.

Next, the control system 422 actuates the robotic manipulator 420 tograsp the valve stem 428, lift the valve stem 428 from the valve stemmeddelivery station, and moves the valve stem 428 to the mounting station416. The location and alignment of the aperture 426, as determined bythe machine vision system, is used by the control system 422 to directthe robotic manipulator 420 to move the valve stem 428 through anynecessary compound, multi-axial movement of the arm 436 to the properorientation for alignment with and insertion through the aperture 426formed in the rim 412 held stationary on the conveyor. The location andalignment of the aperture 426, as determined by the machine visionsystem, is used by the control system 422 to direct the roboticmanipulator 420 to manipulate the valve stem 428 as necessary toposition the valve stem in alignment with the aperture 426 and to insertthe valve stem 428 through the aperture 426 in the rim 412.

When the valve stem 428 is aligned with the aperture 426, the roboticmanipulator 420 urges the valve stem 428 toward the aperture 426 in therim 412 so that the valve stem is inserted through the aperture 426. Itis also possible for the mounting station 416 to include means formoving the rim 412 toward the valve stem 428 and into the aperture 426,rather than holding the rim 412 stationary as the valve stem is urgedthrough the aperture 426.

Insertion of the valve stem 428 through the aperture 426 can also resultin the stem sliding into the end of a nut runner as previously describedwith respect to FIG. 2. The nut runner can then be activated to place anut over the end of the valve stem and rotate to tighten the nut,thereby securing the valve stem in connection with the rim whenappropriate. As previously indicated, only certain specialty valve stemsmust be secured to the rim 412 with a nut. The more commonly used typesof valve stems are secured to the rim 412 merely by urging the valvestem 428 through the aperture 426. Accordingly, the nut runner can bedispensed with on a valve mounting apparatus used with valve stems notrequiring a nut. Alternatively, the nut runner can be retained and thecontrol system programmed to perform or omit the nut tightening stepdepending on the type of valve stem and rim being assembled at anyparticular time.

After the valve stem 428 is secured to the rim 412, the roboticmanipulator 420 is actuated by the control system 422 to clear the rim412, away from the mounting station 416, and the rim 412 is released forfurther movement along the conveyor to a station for subsequentprocessing.

While not shown in FIGS. 7 and 8, as previously indicated the assemblyline can include a plurality of separate stem delivery stations, whereeach station is loaded with a different type of valve stem respectively.The different valve stems can be intended for use with different typesand/or sizes of rims to be handled by the assembly line, and/or thestems can be different types and/or sizes to be alternatively mounted toa single type and/or size of rim. For example, the assembly line can beconfigured to process two different types and/or sizes of rims; a firsttype of rim for passenger cars, and a second type of rim for lighttrucks. In this example, the passenger car rims can be fitted witheither a standard valve stem or a special valve stem having an integralpressure transducer, while all light truck rims are to be fitted with aheavy duty valve stem.

As each rim reaches the gauging station 414, the video camera 430 imagesthe rim and the control system 422 identifies the rim as either a carrim or a truck rim based on programmed physical features as describedabove. The control system 422 then directs the robotic manipulator 420to move to the appropriate valve stem delivery station where the correctvalve stem for that rim is picked up by the robotic manipulator 420. Therobotic manipulator 420 moves the correct valve stem for that rim to themounting station on the conveyor where the rim is being held stationary.The robotic manipulator 420 then aligns the correct valve stem for thatrim with the aperture in the rim whose location was previouslyidentified by the video camera 430. When properly aligned, the roboticmanipulator 420 inserts the correct valve stem 428 through the aperture426 in the rim 412. If necessary, a nut runner is activated to thread anut over the end of the valve stem.

For the passenger car rims, the selection between the standard stem andthe pressure transducer depends on planned production scheduleinformation previously programmed into the control system 422 by a humanoperator using the keypad 422 b or a remote computer 423. The operatorcan select, monitor, and change all phases of operation of the assemblyline using the display screen 422 a and keypad 422 b or the remotecomputer 423. Accumulative production data is stored by the controlsystem 422 and can be reviewed by the operator at any time.

As best seen in FIG. 7, the gauging station can include a motor-drivenrotating table 468 located at the end of the input portion 410 of theconveyor. After being imaged by the video camera 430, the rim 412 can berotated by the motor-driven rotating table 468 until the aperture is ina predetermined location with respect to the conveyor. The finalposition of the aperture with respect to the conveyor can be confirmedby the video camera 430 or by the use of an appropriate optical sensorand a transmitter as are known in the art. The orientation process ofthe rim 412 can be performed to simplify the compound, multi-axismanipulation required by the robotic manipulator to axially align andinsert the valve stem 428 through the aperture 426 in the rim 412. Theangular orientation of the rim 412 may be required under certaincircumstances to optimize performance of the robotic manipulator 420, orto provide sufficient clearance so that the robotic manipulator 420 hasunfettered access to the rim 412 for performing the alignment of thevalve stem 428 with the aperture 426 to allow proper insertion of thevalve stem 428 through the aperture 426 in the wheel rim 412. Theinsertion of the valve stem 428 through the aperture 426 in the wheelrim 412 can be performed at the gauging station 414, or can be performedat a separate mounting station 416 downstream from the gauging station414 along the conveyor.

It should be recognized that the alternative configurations describedwith respect to one embodiment of the invention can be used incombination with one another, or in combination with other embodimentsof the invention as described herein without departing from the presentinvention.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiments but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims, which scope is to be accorded the broadestinterpretation so as to encompass all such modifications and equivalentstructures as is permitted under the law.

1. A method for assembling a valve stem to a wheel rim having anaperture formed therein comprising the steps of: determining a locationof the aperture relative to a gauging station; coaxially aligning acentral axis of the aperture and a longitudinal axis of the valve stemwith respect to one another prior to insertion of the valve stem throughthe aperture; and moving the valve stem relative to the rim along aprogrammable path of travel during the coaxially aligning step and alongthe aligned axes to insert the valve stem through the aperture, the pathof travel defined with a programmable robotic manipulator having an armcapable of compound, multi-axial movement.
 2. The method of claim 1wherein the determining step further comprises the step of: identifyingat least one physical feature of the rim with a machine vision system.3. The method of claim 1 wherein the aligning step further comprises thestep of: selectively moving the valve stem to the gauging station fromone of a plurality of valve stem delivery stations in response to thedetermining step, each delivery station having a differently configuredvalve stem mounted thereon.
 4. The method of claim 1 wherein thedetermining step further comprises the step of: identifying the rim asone of a plurality of different types of rims in response to theinspection with a machine vision system.
 5. The method of claim 1wherein the determining step further comprises the steps of: positioningthe rim on a rotatable table; directing an optical sensor at the rim;rotating the table and the rim; and stopping rotation of the table andrim when the optical sensor is directed at the aperture.
 6. The methodof claim 5 further comprising the step of: inserting a mechanical probeinto the aperture to verify the location of the aperture beforeinsertion of the valve stem through the aperture.
 7. The method of claim6 wherein the inserting step further comprises the step of: moving therim with the probe to align the aperture with respect to the probe. 8.The method of claim 1 further comprising the step of: tightening a nutover a threaded portion of the valve stem extending from the rim afterthe valve stem has been inserted with respect to the aperture.
 9. Themethod of claim 8 wherein the nut is tightened to the valve stem by anut runner mounted on the robotic manipulator.
 10. The method of claim 8wherein the nut is tightened to the valve stem by a nut runner mountedadjacent to the gauging station.
 11. The method of claim 1 furthercomprising the step of: conveying valve stems to a delivery station in aserial fashion with conveying means.
 12. The method of claim wherein themoving step further comprises the steps of: holding the rimsubstantially stationary; and urging the valve stem toward the rim withthe robotic manipulator.
 13. The method of claim 1 further comprisingthe step of: moving the rim and attached valve stem from the gaugingstation to a subsequent processing station such that the rim is orientedwith the valve stem in a predetermined angular position relative to thesubsequent processing station.
 14. The method of claim 1 furthercomprising the step of: grasping the valve stem with the roboticmanipulator and moving along the path of travel in response tocomputer-controlled signals.
 15. The method of claim 14 furthercomprising the step of: actuating the robotic manipulator to move thevalve stem to the rim located at a delivery station.
 16. The method ofclaim 1 further comprising the step of: grasping the valve stem with therobotic manipulator and having a valve-stem- gripper-attachmentarticulatable and positionable to be in a predetermined orientation withrespect to the aperture in the rim.
 17. The method of claim 16 furthercomprising the step of: orienting the aperture of the wheel rim in apredetermined location with the respect to thevalve-stem-gripper-attachment as a result of articulation andpositioning of the valve-stem-gripper-attachment by the roboticmanipulator prior to the inserting step.
 18. The method of claim 16further comprising the step of: orienting the aperture of the wheel rimin a predetermined location with respect to the gauging station as aresult of rotational movement of the rim until the aperture is properlylocated with respect to the gauging station prior to the inserting step;and the inserting step performed with the valve-stem-gripper-attachmentin a predetermined position with respect to the gauging station as aresult of articulation and positioning of thevalve-stem-gripper-attachment by the robotic manipulator prior to theinserting step.
 19. An apparatus for assembling a valve stem to a wheelrim having an aperture formed therein comprising: means for determininga location of the aperture relative to a gauging station; means forcoaxially aligning the central axis of the aperture and a longitudinalaxis of the valve stem with respect to one another prior to insertion ofthe valve stem through the aperture; and means for moving the valve stemrelative to the rim along a programmable path of travel includingalignment of the central axis of the aperture with the longitudinal axisof the valve stem and along the aligned axes to insert the valve stemthrough the aperture, the path of travel defined with a programmablerobotic manipulator having an arm capable of compound, multi-axialmovement.
 20. The apparatus of claim 19 wherein the means fordetermining further comprises: a machine vision system to identify atleast one physical feature of the rim.
 21. The apparatus of claim 20wherein the aligning means further comprises: the robotic manipulator toselectively move the valve stem from one of a plurality of deliverystations having different valve stems mounted thereon in response to theidentification by the machine vision system.
 22. The apparatus of claim19 wherein the means for determining further comprises: a machine visionsystem to identify the rim as being one of a plurality of differentrims.
 23. The apparatus of claim 19 wherein the means for determiningfurther comprises: a rotatable table for selectively rotating the rim;and an optical sensor to detect the location of the aperture as the rimis rotated.
 24. The apparatus of claim 23 further comprising: a probeextendable through the aperture after the rim has been rotated to verifythe location of the aperture prior to insertion of the valve stemthrough the aperture.
 25. The apparatus of claim 24 wherein the probe isoperable to reposition the rim to bring the aperture into alignment withthe probe.
 26. The apparatus of claim 19 further comprising: means fortightening a nut over a threaded portion of the valve stem extendingfrom the rim to secure the valve stem to the rim.
 27. The apparatus ofclaim 26 wherein the means for tightening further comprises: a nutrunner mounted on the robotic manipulator.
 28. The apparatus of claim 26wherein the means for tightening further comprises: a nut runner mountedadjacent to the gauging station.
 29. The apparatus of claim 19 furthercomprising: means for supplying valve stems in a serial fashion to adelivery station.
 30. The apparatus of claim 19 wherein the means formoving further comprises: the robotic manipulator to urge the valve stemtoward the rim.
 31. The apparatus of claim 19 further comprising: therobotic manipulator for moving the rim and attached valve stem from agauging station where the valve stem is mounted with respect to theaperture to a processing station while maintaining the valve stem in apredetermined angular position relative to the processing station. 32.The apparatus of claim 19 further comprising: means for grasping thevalve stem with the robotic manipulator and having avalve-stem-gripper-attachment articulatable and positionable to be in apredetermined orientation with respect to the aperture in the rim. 33.The apparatus of claim 32 further comprising: means for orienting theaperture of the wheel rim in a predetermined location as a result ofarticulation and positioning movement of the valve stem with the roboticmanipulator.
 34. The apparatus of claim 32 further comprising: means fororienting the aperture of the wheel rim in a predetermined location as aresult of movement of the rim at the gauging station prior to the valvestem being inserted by the robotic manipulator.
 35. A method forassembling a valve stem to a wheel rim having an aperture formed thereincomprising the steps of: operably engaging the valve stem with aprogrammable robotic manipulator; moving the valve stem relative to therim along a programmable path of travel; coaxially aligning the valvestem and the aperture; and inserting at least a portion of the valvestem through the aperture in the rim, wherein the path of travel isdefined with the programmable robotic manipulator.
 36. The methodaccording to claim 35 further comprising determining the location of thevalve stem aperture in the rim prior to insertion of the valve stem inthe aperture.
 37. The method according to claim 36 wherein the step ofdetermining the location of the aperture further comprises the step ofinserting a mechanical probe into the aperture prior to insertion of thevalve stem through the aperture to verify the location of the aperture.38. The method according to claim 35 further comprising the steps ofoperably engaging the valve stem and moving the valve stem towards therim.
 39. The method according to claim 35 further comprising the step ofsecuring the valve stem to the rim by tightening a nut over a threadedportion of the valve stem extending from the rim.
 40. The method ofclaim 35 further comprising the step of: grasping the valve stem withthe robotic manipulator and having a valve-stem-gripper-attachmentarticulatable and positionable to be in a predetermined orientation withrespect to the aperture in the rim.
 41. The method of claim 40 furthercomprising the step of: orienting the aperture in the rim to apredetermined location during movement of the valve stem with therobotic manipulator as a result of articulation and positioning of thevalve-stem-gripper-attachment.
 42. The method of claim 40 furthercomprising the step of: orienting the aperture in the rim to apredetermined location at a station prior to the inserting step.
 43. Anapparatus for assembling a valve stem to a wheel rim having an apertureformed therein comprising: means for operably engaging the valve stem;means for moving the valve stem relative to the rim along a programmablepath of travel; and means for coaxially aligning the valve stem and theaperture to insert at least a portion of the valve stem through theaperture in the rim, wherein the path of travel is defined with aprogrammable robotic manipulator.
 44. The method apparatus of claim 43further comprising means for determining the location of the valve stemaperture in the rim prior to insertion of the valve stem into theaperture.
 45. The apparatus of claim 43 further comprising: means forgrasping the valve stem with the robotic manipulator and having avalve-stem-gripper-attachment articulatable and positionable to be in apredetermined orientation with respect to the aperture in the rim. 46.The apparatus of claim 45 further comprising: means for orienting theaperture of the wheel rim in a predetermined location with respect tothe valve-stem-gripper-attachment as a result of articulation andpositioning of the valve-stem-gripper-attachment by the roboticmanipulator prior to inserting the valve stem.
 47. The apparatus ofclaim 45 further comprising: means for orienting the aperture of thewheel rim in a predetermined location with respect to a gauging stationas a result of rotational movement of the rim until the aperture islocated with respect to the gauging station prior to inserting the valvestem; and the grasping means including the valve-stem-gripper-attachmentbeing in a predetermined position with respect to the gauging station asa result of articulation and positioning of thevalve-stem-gripper-attachment by the robotic manipulator prior toinserting the valve stem.